Elastomer
Processing
Part 2

Types
of Polymerization Reactions

1. Condensation
Polymerization-
yields polymers with repeating units having fewer atoms than the monomers
from which they are formed. This reaction generally involves the elimination
of small molecules such as H2O or HCl.

2. Addition
Polymerization

3. Chain
Polymerization/Free Radical Polymerization-

A. Initiation: formation of free radicals by scission of a single
bond (homolysis), or by the transfer of a single electron to or
from an ion or molecule (redox).

Bulk Polymerization-
involves only the monomer and a monomer-soluble initiator.

Solution
Polymerization-
a solvent lowers the viscosity, assisting heat transfer and reducing
the likelihood of auto-acceleration.

Suspension
Polymerization-
reaction mixture is suspended as droplets in an inert medium. Polymer
particles are produced in the form of beads in the range of 0.1 to 2
mm in diameter.

Emulsion
Polymerization-
the initiator is not soluble in the monomer but soluble only in the
aqueous dispersion medium. Polymer is produced in the form of a latex
with particles in the range of 0.05 to 1 micron.